The present invention relates to a catheter insertion assembly for use in placing a catheter into a patient with minimal trauma to the tissues of the patient, particularly at the insertion site, and with a reduced likelihood of air embolism.
Peripherally inserted central venous catheters (“CVCs”) have been utilized by clinicians for several decades. Catheter insertion by the Seldinger technique has been used even longer, primarily for the insertion of subclavian and other chest inserted catheters. The Seldinger technique begins with obtaining access to a blood vessel with a needle. The needle is hollow and, after it is determined that the needle has been inserted into the appropriate blood vessel, a wire is passed through the needle bore into the blood vessel. The wire is often referred to as a “guidewire” since its ultimate purpose is to guide a catheter into place. Once it is determined that the distal end of the guidewire is properly placed within the blood vessel, the needle is removed by backing the needle over the guidewire while leaving the guidewire in place. Proper placement of the guidewire may be verified by fluoroscopy or other imaging method.
The guidewire is then used to guide a dilator, if needed, into the blood vessel to widen the opening through the skin and subcutaneous tissue. After use, the dilator is removed while the guidewire is still held in place. Multiple dilators may be used, one after the other, until the opening is large enough to receive a catheter introducer. The catheter introducer is a short hollow tube which is placed in the opening. The introducer is sometimes disposed about the largest dilator and inserted along with the dilator. When the dilator is removed the introducer remains. Alternatively, the catheter introducer is inserted subsequent to the removal of the final dilator. With the introducer in place, the catheter is advanced over the guidewire and through the introducer. When catheter insertion is accomplished, the introducer is pulled out of the incision and split according to the manufacturer's usage directions so that it can be removed from around the catheter. The guidewire is removed either prior to or after the removal of the introducer.
One reason why a catheter introducer is necessary is that most catheters are soft and subject to bending and kinking. Inserting a soft and pliable catheter through the tissue of an insertion site and into the vasculature of a patient, even over a guidewire and after the use of one or more dilators, is difficult. Such an insertion can result in damage to the catheter, to the patient or both.
One of the complications encountered during the insertion of catheters, and particularly insertion of catheters into the patient's thoracic cavity, i.e. adjacent the heart, is the possibility of air embolism. An air embolism is the obstruction of a blood vessel by an air bubble. When inserting a catheter into the vasculature of a patient utilizing the Seldinger technique, a path from the atmosphere to the vasculature is created. While it is usually possible to keep the path sufficiently obstructed, this is not always the case. Whether through necessity or accident, this path is sometimes opened. If, while this path is opened, the patient takes a deep breath, air will be sucked into the central vessels through the open path. This results in an air embolism. Air embolism is potentially a very serious complication and may be fatal.
The likelihood of an air embolism is greatest when a catheter introducer is used. One reason for this is that the diameter of a catheter introducer is usually relatively large, i.e. 12 french or more, in order to fulfill its function of allowing insertion of the catheter. It would defeat the purpose of the catheter introducer to include an obstruction therein; as a clear path from outside of the patient's body to the patient's vasculature needs to be available for the catheter to be inserted. Thus, a need exists for a catheter insertion assembly that reduces insertion trauma and the likelihood or severity of air embolism during catheter insertion into a patient. A need also exists for a catheter insertion assembly that obviates the need for a catheter introducer.